fini the T_NEXUS during node_free

it's too early in set_delivered() because set_closed() calls
set_delivered() on a nexus when all children are already devivered, but
that can happen from within the nexus node's fsm.

we will add extra finis when it's safe in a later commit

src/vdp_pesi.c

@@ -493,7 +493,13 @@ node_free(struct req *req, struct node *node)
 		fini_data(req, node);
 		break;
 	case T_CRC:
+		break;
 	case T_NEXUS:
+		if (node->req == NULL || node->parent == NULL)
+			break;
+		// XXX SHOULD HAPPEN EARLIER
+		req_fini(node->req, req->wrk);
+		node->req = NULL;
 		break;
 	default:
 		INCOMPL();
@@ -706,11 +712,8 @@ set_delivered(struct bytes_tree *tree, struct node *node)
 		}
 
 		CHECK_OBJ_NOTNULL(node->req, REQ_MAGIC);
-		if (node->parent != NULL) {
+		if (node->parent != NULL)
 			VDP_close(node->req);
-			req_fini(node->req, req->wrk);
-			node->req = NULL;
-		}
 	}
 
 	node->state = ST_DELIVERED;